According to to Blue Coat, malware is starting to be adapted by hackers in relatively rapid lifecycles – the average lifespan of a typical piece of malware dropped from seven hours in 2007 to just two in 2009, notes the report.

As a result of this faster malware lifecycle, the study says that defences that require patches and downloads are simply unable to keep pace.

Increased reliance on social networking for communication, says Blue Coat, means there is less reliance on web-based email, which dropped in popularity from fifth place in 2008 to ninth place in 2009.

And, the report adds, exploiting user trust drives most common threats. The two most common web-based threats in 2009 – the fake antivirus software and the fake video codec – both exploited user trust on the internet, search engines and social networks.

According to Blue Coat, these were not the 'drive-by' attacks of recent years, nor did they require a vulnerability to exploit other than human behaviour.